Here is a list of all files with brief descriptions:

[detail level 12]

src
account.h
amount.h	Basic type for handling commoditized math: amount_t
annotate.h	Types for annotating commodities
balance.h	Basic type for adding multiple commodities together
chain.h
commodity.h	Types for handling commodities
compare.h
context.h
convert.h
csv.h
draft.h
emacs.h
error.h
expr.h
exprbase.h
filters.h
flags.h
format.h
generate.h
global.h	Contains the top-level functions used by main.cc
gpgme.h	A utility class for reading encrypted journal data
history.h	Types for managing commodity historys
item.h
iterators.h
journal.h
lookup.h
mask.h	Regular expression masking
op.h
option.h	Basic type and macros for handling command-line options
output.h
parser.h
pool.h	Types for managing commodity pools
post.h
precmd.h
predicate.h
print.h
pstream.h
ptree.h
pyinterp.h	Basic type for Python API
pyutils.h	Basic utilities for Python API
query.h
quotes.h
report.h
scope.h
select.h
session.h
stats.h
stream.h	A utility class for abstracting an output stream
strptime.h	Implements strptime under Windows
temps.h
timelog.h
times.h	Datetime_t and date_t objects
token.h
unistring.h
utils.h	General utility facilities used by Ledger
value.h	Abstract dynamic type representing various numeric types
xact.h